Disconnects are used downhole to release from a tool once it is set. If a work string delivering a tool gets stuck before or after delivery of a tool it is also advantageous to be able to release from the tool so that the string can be removed. After the string is removed a fishing or milling tool can be deployed to remove the stuck tool or portion of the string below the disconnect.
The two components are selectively held engaged against tension by one or more retainers such as dogs that extend through a window in one component into a recess in an opposing component and selectively held in that position by a sleeve or piston. An example of such a disconnect is U.S. Pat. No. 7,395,862 which has a dog 56 or U.S. Pat. No. 6,148,916 using a disconnect in the context of releasing a perforating gun where the release actuates the gun to fire.
Some tools release by applied tensile force above a predetermined value and can be locked against release at that value or unlocked using a remote signal such as an acoustic signal so that if the predetermined tension is then applied the connection will release. An example of this general design in an application of a fail-safe disconnect from a subsea well is U.S. Pat. No. 7,240,734, notably the unlatch tool 28. U.S. Pat. No. 6,880,637 uses hydrostatic pressure to actuate a release mechanism for a perforating gun. An electronic firing head responds to sonic signals to fire the gun. U.S. Pat. No. 6,591,912 shows the use of gas pressure developed from shooting off a perforating gun to actuate a release mechanism. U.S. Pat. No. 5,967,231 releases a wiper plug and delivers a signal that the plug has been released. US publication 2008/0041597 combines in a single assembly a release feature and a data gathering and transmission feature using a variety of telemetry techniques such as pressure pulses, acoustic or electromagnetic signals as described in paragraph 63.
The present invention operates a disconnect using preferably a pressure pulse signal that is processed at the disconnect. Upon receipt of the predetermined release signal a valve is operated to allow either annulus or tubing fluid pressure act against a piston on one of its ends with the opposite end preferably exposed to a low pressure or atmospheric chamber or tubing pressure. The piston movement breaks a shear pin and positions a recess opposite a locking dog to enable the separation of the two previously held components. Activation can come from the tubing or the annulus or both. The piston can be an annular sleeve or one or more rods. Piston movement can also be used in other applications to open or close a tubular wall port. Those skilled in the art will gain further insight into the present invention from a review of the detailed description of the preferred embodiment and the associated FIG. while recognizing that the full scope of the invention can be found in the appended claims.